We already know about the greatest racetracks that are no more — what about the greatest long-gone races themselves?

My personal favorite race that is no more is the Race of Two Worlds, also known as Monzanapolis. It was a 500 mile race held just twice in 1957 and 1958 on the Monza banking. The idea was to pit the best drivers in America against the best drivers in Europe. The speeds were so high that many of the world's best drivers refused to show up because they figured it was too dangerous. Specifically, they called it "mass suicide." Remember, this was in the late '50s, when driver deaths were commonplace.

Monzanapolis was so fast that Firestone had to bring over new tires just to see if they wouldn't explode running at an average lap speeds of just over 165 miles an hour. This was a good twenty miles an hour faster than the average lap speed at Indy at the time. Here's a contemporary newsreel on the testing.

The top trap speed in 1957 was a scarcely-believable 195 miles an hour, 8W.Forix reports.

After 1958 everyone came to their senses and cancelled the race. It stands as one of the most reckless motor races ever seen.

What do you think was the greatest car race that doesn't exist any more?